Radio signaling system



RADIO S IGNALING SYSTEM Filed March 28. 1929 TOAUDIO HI'I'I'FL- INVENTOR'25 same radio frequency.

Patented June 6, 1933 WILLIAM L. SEIBERT, or ronrrmoiv vrou'rn ewannsnv.

RADIO SIGNALING SYSTEM 7 Application filed March 28, 1929 Serial No.350,749.

(GRANTED unnnn rnn ACT or MARCH 3, 1883, As mammal) APRIL at, 11925; 370as. 757) The in entiOn described herein may be manufactured and used byor for the Government for governmental purposes without the payment tome of any royalty thereon.

'6 This invention relates to radio communication systems, and moreparticularly to transmitting and receiving circuits using vacuum tubes.The systems used previously have ordinarily included substantiallycomplete separate circuits and tubes for transmitting and receiving.

One of the objects-of my invention is to utilize a single vacuum tubeand associated circuits for both transmitting and receiving, thuseffecting a reduction in quantity of apparatus and simplification ofcircuits required.

A further object is to provide automatic 7 change of plate current asrequired for the 29 purposes of transmitting and receiving.

A still further object is to utilize a single oscillating tube circuitfor both transmission and reception, thus enabling the transmitter andreceiver to operate on substantially th A clear understanding of theinvention may be had by reference to the following description of acomplete embodiment which is illustrated in the accompanying drawing.

39 In this drawing there is shown a schematic arrangement of a vacuumtube oscillator connected to a tuned loop antenna circuit. A telegraphsending key, included in the plate circuit, operates to short-circuitthe series resistance in the plate circuit so that full plate voltage isimpressed on the tube while transmitting and reduced plate voltage isprovided while receiving, as is necessary to obtain sensitive reception.

Referring now to the drawing, a vacuum tube oscillator of the usual formis represented at 1. This is connected to the tuned circuit consistingof loop antenna 2, fixed ratio condensers 3' and 4, and variable con- 4denser for frequency adjustment 5. Blocking condenser 6 serves toinsulate the d. c. plate potential from the tuned circuit. The negativegrid bias potential is maintained by potentiometer 7 thru radiofrequency choke coil 8. The potentiometer 7 is by-passed for radiofrequencies by condenser 9. The plate current is supplied from thebattery shown, the plate circuit including 1 0, the primary of an audiotransformer providing coupling toan audio amplifier. The plate circuitalso includes Ia large resistor lland its audio signal by-passcondenser-12. .The. radio frequency choke coil 18v and condenser 14serve to preventshort-circuiting the radio frequency potentials, presentin theloop circuit. A'telegraphsending key 15 operates 'to short-circuitthe primary -10 of the v I audio transformer andthelargefseries-re:

sistance 11, so that fullplate voltage will. be impressed on the tubefor-transmitting.

in the tuned loop circuit. When the tele-- A large radio frequencycurrent isthen setup graphsending key 15 is opened, the plate 7 currentis greatly reduced and the circuit oscillates weakly, as is required toobtain;

sensitivity for heterodyne reception: of signals. The adjustment of 1the oscillation amplitude, as required for most sensitive reception, isprecisely controlled-by the grid potentiometer-7.

The circuit then operates as, a powerful radio'transmitter when thesending key is closed,.and as a sensitive heterodyne-radio receiver whenthe sending key is open. As the tuned circuit was the, same for; bothtransmission and reception, theufrequency of the oscillations Wassubstantially 'unchanged for sending and receiving.-

' Communication is then quickly establishedbetween two stations. StationA calls station B; Station. B tunes to obtainbeat note of perhaps 1000cycles and answers call. Station .A will then hear similar beat note of,approximately 1000 cycles, without further tuning adjustment. Thetransmitting frequencies used by the two'stations will then differ onlyby' the audio beat. frequency necessary for heterodyne reception.

f The operation of two or more. tubes with plates and grids each inparallel will, of course, change in no way the objects and claimscontained herein, which mention one, or a single tube. 1

WVhile I. have described certain forms of my invention in detail, andwhile I have pointed out certain of the most obvious principles andpurposes thereof, I do not intend that the language employed in thefollowing claims shall be limited to the precise features described, butI intend that the claims shall be construed to cover all combinationswhich are fairly included in the language thereof, when read in View ofthe prior art regardless of the details and functionsmentioned in thedescription or illustrated in the drawing.

Iclaim: M

1. A radio signaling system, comprising a singletransmitting andreceiving circuit; an electron tube having a plate circuit associatedwith said single circuit; means operative with the plate circuit tocause said tube to oscillate strongly while transmitting; a source ofpotential in the plate circuit and means in said circuit forsubstantially reduc ing the potential to cause said tube to oscillateweakly while receiving.

2. A radio signaling system, comprising a single transmitting andreceiving circuit; an electron tube in said circuit; means to cause saidtube to oscillatestrongly while transmitting; and means to cause thetube to oscillate weakly while receivin A radio signaling system,comprising a combined transmitting and receiving circuit; an electrontube having a plate circuit operatively associated with said combinedcircuit; a source of potential in said plate circuit; means operative insaid plate circuit to control the value of said potential to cause saidtube to oscillate strongly when transmitting and to oscillate weakly asa selfheterodyne detector when receiving.

4. A radio telegraph signaling svstem, comprising a single tuned circuitadapted both for transmitting and receiving; an electron tube having aplate circuit operatively associated with said single circuit; a sourceof potential in the plate circuit, and means in said circuit to controlthe value of the potential; and a telegraph key operative with saidcontrol means to produce strong oscillations in the tube whiletransmitting and weak oscillations while receiving. i

5. A radio signaling system, comprising a single tuned circuit fortransmitting and receiving; a single electron tube adapted to oscillateinto said circuit while both transmitting and receiving; means operativewith said tube to cause strong oscillations while transmitting and Weakoscillations while receiving. I

6. A radio signaling system, comprising a combined transmitting andreceiving circuit; a tuned antenna circuit associated with said combinedcircuit; a single electron tube included in said combined circuit andadapted to oscillate into said antenna circuit; means to cause said tubeto oscillate strongly ceiving; means in the plate circuit to cause saidtube to oscillate strongly while transmitting and weakly Whilereceiving; and

means in the tunedicircult to malntain a substantially constantfrequency both while transmitting and receiving. In testimony whereof Iafiix my signature.

WILLIAM L. SEIBERT.

